Single-motor type transmission unit of an office machine

ABSTRACT

A transmission unit mounted on the machine base of an office automation machine and covered with a cover and controlled to turn a document feeding control roller through a first driven gear set and/or a thermal paper letting-off control roller through a second driven gear set, including motor, a drive gear turned by the motor, a gear transmission mechanism which includes a first planet gear, a second planet gear, and a sector gear respectively turned by the drive gear to turn the first driven gear set and/or the second driven gear set, and a memory transmission setting mechanism which includes an electromagnetic valve, and a reciprocating rod reciprocated by the electromagnetic valve and having a front notch at a front end thereof, the front notch of the reciprocating rod being forced into engagement with the gear shaft of the first planet gear to disengage the first planet gear from the first driven gear set when the fax machine is set at the memory transmission mode.

BACKGROUND OF THE INVENTION

The present invention relates to fax machines, and relates more particularly to the single-motor transmission unit of a fax machine which prevents the gears from being jammed, permits jammed paper to be conveniently pulled out of the machine, and allows the fax machine to execute the memory transmission mode.

The transmission unit of a single motor type fax machine comprises a first roller and a second roller. The first roller and the second roller are simultaneously rotated to advance the thermal paper during the copy or receiving mode. When at the transmission mode, only the first roller is rotated to feed document. After the copy or receiving mode, the thermal paper is cut automatically or manually. When the thermal paper is cut off, the leading end of the rest thermal paper extends over the thermal printing head which cannot be used for printing. This structure of single motor type fax machine cannot execute the memory transmission mode as a dual-motor type fax machine. Furthermore, because the gears for power transmission from the motor to the first roller are maintained connected when a paper is jammed in the transmission unit, it is difficult to pull the jammed paper out of the transmission unit of the fax machine.

SUMMARY OF THE INVENTION

The present invention has been accomplished to provide a transmission unit which eliminates the aforesaid drawbacks. According to one aspect of the present invention, the transmission unit is mounted on the machine base of the fax machine and covered with a cover, comprised of a gear transmission mechanism, a first roller having a driven gear set at one end, and a second roller having a driven gear set at one end, wherein the gear transmission mechanism comprises a motor, a rounded seat raised from the machine base, a drive gear mounted on the rounded seat and coupled to the motor, a first annular gear holder revolvably mounted around the rounded seat and having an upright gear shaft, a second annular gear holder revolvably mounted around the rounded seat and having two upright gear shafts, an auxiliary gear mounted on the machine base, a first planet gear revolvably mounted around the gear shaft of the first annular gear holder and driven by the drive gear to turn the driven gear set of the first roller, a second planet gear revolvably mounted around one upright gear shaft of the second annular gear holder and meshed between the drive gear and the auxiliary gear and driven by the drive gear to turn the driven gear set of the second roller, and a sector gear meshed with the drive gear and forced to turn the driven gear set of the second roller through a fixed angle after a copy or receiving mode. Because the planet gears are mounted on a respective annular gear holder which is revolvably mounted on the rounded, the planet gears are forced to disconnect from the driven gear set of the first roller and the driven gear set of the second roller respectively when a jammed paper is pulled backwards. Therefore, a jammed paper can be easily pulled out of the fax machine. According to another aspect of the present invention, the transmission unit further comprises a memory transmission setting mechanism which comprises an electromagnetic valve, and a reciprocating rod reciprocated by the electromagnetic valve and having a front notch at a front end thereof. The front notch of the reciprocating rod is forced into engagement with the gear shaft of the first planet gear to disengage the first planet gear from the driven gear set of the first roller when the fax machine is set at the memory transmission mode.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an assembly view of the gear transmission unit of a fax machine according to the present invention;

FIG. 2 is an exploded view of the gear transmission unit shown in FIG. 1;

FIG. 3 is a plain view of the gear transmission unit shown in FIG. 1, showing the motor turned clockwise;

FIG. 4 is another plain view of the gear transmission unit shown in FIG. 1, showing the motor turned counter-clockwise;

FIG. 5 is still another plain view of the gear transmission unit shown in FIG. 1, showing the sector gear forced into engagement with the power input gear of the driven gear set of the second roller and turned; and

FIG. 6 is still another plain view of the gear transmission unit shown in FIG. 1, showing the front notch of the reciprocating rod of the memory transmission setting mechanism forced into engagement with the gear shaft of the first annular gear holder, and the first planet gear disengaged from the driven gear set of the first roller.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIGS. 1 and 2, the transmission unit of a fax machine in accordance with the present invention is mounted on the machine base 4, and comprised of a gear transmission mechanism 1, a first roller 2, a second roller 3, and a memory transmission setting mechanism 5.

The gear transmission mechanism 1 comprises a motor 10, a drive gear 11 mounted on a rounded seat 40 at one side of the machine base 4 and coupled to the output shaft of the motor 10, a first annular gear holder 15 revolvably mounted around the rounded seat 40 and having an upright gear shaft 151, a second annular gear holder 16 revolvably mounted around the rounded seat 40 and having a first upright gear shaft 161 and a second upright gear shaft 162, a first planet gear 12 revolvably mounted around the gear shaft 151 of the first annular gear holder 15 and meshed with the drive gear 11 at one side, a second planet gear 13 revolvably mounted around the first upright gear shaft 161 of the second annular gear holder 16 and meshed with the drive gear 11, a sector gear 14 revolvably mounted around the second upright gear shaft 162 of the second annular gear holder 16 and meshed with the drive gear 11, and an auxiliary gear 18 meshed with the second planet gear 13.

The first roller 2 and the second roller 3 are respectively disposed at two opposite sides by the drive gear 11, having a respective driven gear set 20, 30 respectively mounted on the machine base 4 at two opposite sides relative to the drive gear 11, and adapted to receive driving power from the drive gear 11 through the planet gears 12, 13 and the sector gear 14. The driven gear set 20 of the first roller 2 comprises a first idle wheel 21 and a second idle wheel 22.

The memory transmission setting mechanism 5 (see also FIG. 3) is mounted on the machine base 4 at one side adjacent to the gear transmission mechanism 1, comprised of an electromagnetic valve 50, a reciprocating rod 51 reciprocated by the electromagnetic valve 50 and having a longitudinal slot 52 and a front notch 55 at the front end, and two upright guide rods 53, 54 raised from the machine base 4 and respectively inserted into the longitudinal slot 52 of the reciprocating rod 51 to guide its reciprocating movement. During the memory transmission mode, the electromagnetic valve 50 is driven to push the reciprocating rod 51 outwards, causing the front notch 55 of the reciprocating rod 51 to be forced into engagement with the gear shaft 151 of the first annular gear holder 15.

When the gear transmission mechanism 1, the driven gear sets 20, 30 are installed, a cover 42 is fastened to the machine base 4 by screws 41 and covered over the gear transmission mechanism 1 and the driven gear sets 20, 30. The cover 42 has arched guide slots 43, 44, 45 which receive the upright gear shaft 151 of the first annular gear holder 15 and the upright gear shafts 161, 162 of the second annular gear holder 16 to guide the movement of the first planet gear 12, the second planet gear 13, and the sector gear 14 along the teeth of the drive gear 11 within a fixed angle respectively.

Referring to FIG. 3, when the motor 10 turns clockwise during the transmission mode of the fax machine, the second roller 3 does no work, the first planet gear 12 of the gear transmission mechanism 1 is forced into engagement with the first idle wheel 21 of the driven gear set 20 of the first roller 2, thereby causing the first roller 2 to be turned to feed document forwards.

Referring to FIG. 4, when the motor 10 turns counterclockwise during the receiving or copy mode of the fax machine, the first planet gear 12 is forced into engagement with the second idle wheel 22 of the driven gear set 20 of the first roller 2, and the second planet gear 13 is forced into engagement with the power input gear 31 of the driven gear set 30 of the second roller 3, and therefore the first roller 2 and the second roller 3 are simultaneously turned to advance the thermal paper.

Referring to FIG. 5, when a receiving or copy operation is completed, the motor (step motor) 1O is turned clockwise through a certain number of steps to force the sector gear 14 into engagement with the power input gear 31 of the driven gear set 30 of the second roller 3, causing the second roller 3 to be turned reversely through a certain angle, and therefore the thermal paper is turned to retract its leading end which passes over the thermal printing head. This design saves the consumption of the thermal paper.

Referring to FIG. 6, during the memory transmission mode, the front notch 55 of the reciprocating rod 51 is forced by the electromagnetic valve 50 into engagement with the gear shaft 151, causing the first planet gear 12 to be disengaged from the idle wheel 21 or 22, to prevent the first roller 2 from being turned to feed document upon receiving of incoming data during the memory transmission mode.

Further, because the first planet gear 12 and the second planet gear 13 are respectively mounted on the first annular gear holder 15 and the second annular gear holder 16, they are movable relative to each other, and the engagement between the drive gear 11 and the planet gears 12, 13 can be respectively adjusted without causing an interference, and therefore jammed document can be easily pulled out of the machine. Because the annular gear holders 15, 16 are revolvably mounted around the rounded seat 40, when document is pulled back, the planet gears 12, 13 are forced to disconnect from the driven gear sets 20, 30, therefore the drive gear 11 is disengaged from the driven gear sets 20, 30, permitting the first roller and the second roller to be freely rotated.

It is to be understood that various modifications and changes could be made thereunto without departing from the spirit and scope of the invention disclosed. 

What the invention claimed is:
 1. A paper advancement system for an office machine operable in a plurality of operational modes comprising:(a) a machine base frame; (b) a first roller assembly coupled to said machine base frame for advancing a paper article engaged therewith in at least one of a plurality of advancement directions responsive to said operational mode of said office machine, said first roller assembly including a first roller portion extending axially from a first driven gear set; (c) a second roller assembly coupled to said machine base frame for advancing a paper article engaged therewith in at least one of said plurality of advancement directions responsive to said operational mode of said office machine, said second roller assembly including a second roller portion extending axially from a second driven gear set; (d) a gear transmission assembly coupled to said machine base frame for driving said first and second roller assemblies said gear transmission assembly including:(1) a motor; (2) a substantially round seat member projecting from said machine base frame; (3) a drive gear member driven by said motor, said drive gear member being coaxially disposed relative to said seat member; (4) gear holder means rotatably coupled to said seat member, said gear holder means having first, second, and third upright gear shafts projecting therefrom; (5) an auxiliary gear member mounted to said machine base frame; (6) a first planet gear member rotatably coupled to said first upright gear shaft of said gear holder means, said first planet gear engaging said drive gear member and said first driven gear set; (7) a second planet gear member rotatably coupled to said second upright gear shaft of said gear holder means, said second planet gear member engaging said drive and auxiliary gear members and said second driven gear set; and, (8) a sector gear member rotatably coupled to said third upright gear shaft of said gear holder means, said sector gear member engaging said drive gear member and said second driven gear set; (e) a cover mounted to said machine base frame, said cover having at least three arcuate slots formed therein, said cover receiving respectively through said arcuate slots said first, second, and third upright gear shafts of said gear holder means for guiding the angular displacement thereof; and, (f) a memory transmission assembly coupled to said machine base frame and said gear transmission assembly for selectively disabling said advancement of a paper article during at least one of said operational modes of said office machine, said memory transmission assembly including:(1) an electromagnetic valve; (2) a reciprocating rod member coupled to said electromagnetic valve to be displaceable thereby between first and second positions, said reciprocating rod member having formed thereon a front notch portion for disengaging said first planet gear from said first driven gear set when said reciprocating rod member is in said second position.
 2. The paper advancement system as recited in claim 1 wherein said machine base frame has formed thereon at least one upright guide rod projecting therefrom.
 3. The paper advancement system as recited in claim 2 wherein said reciprocating rod member of said memory transmission assembly has formed therein a longitudinally extended guide slot receiving said upright guide rod of said machine base frame. 